Portal 2

I just got Portal 2 a few days ago and am really excited to play it. Unfortunately, I have encountered an issue that many people seem to have, but few have solved. After loading Portal 2, my computer shows just a black screen, but I can hear the noises. One solution to the issue that I found was to enable the developer console and type this in: "mat_postprocess_enable 0" This worked to some degree, but the image is flickery and laggy. I noticed in the developer console, it says in red lettering, "***** Trying to get a pixel shader that failed loading!" I have done some research on this issue, but come up blank. I would like to tackle the problem of this error specifically, and avoid simply getting a new graphics card if possible. Thanks!

Hey, can you please, please help me get rid of the black screen, because I really do not have a clue how to solve it myself tough you seem to have at least to an extend of wich I would be happy as the black screens just gets me frustrated.Thanks in already

1. Right-click Portal 2, then click Properties. 2. Click Local Files (the middle tab), then Browse Local Files3. Right-click Portal 2 Application, then properties (note: you must right-click the words "Portal 2" or you'll get the wrong menu).4. In the Properties tab, click Compatability (2nd to left tab)5. Check "Run this program in compatability mode", then select "Windows 7" in the drop-down menu.6. Play the game

And after you quit the game & decide you want to play again:

7. Repeat steps 1 - 58. For "Run this program in compatability mode for:", change it to "Windows Server 2003 (Service Pack 1)"9. Play the game.